Key Facts:

    • A collapsed lung means air is leaking out of your lung and getting trapped in your chest. This trapped air then squishes your lung, and that makes it hard to breathe. 
    • Pneumothorax is the medical term for either a partial or complete lung collapse.
    • There are two main types of pneumothorax: spontaneous and traumatic. Spontaneous lung collapse occurs without an injury. Traumatic lung collapse is due to an injury or puncture during a medical procedure.
    • You are at a higher risk of having another pneumothorax after you’ve already had one.

What Causes a Collapsed Lung?

There are several different types of pneumothorax that fall under the two main categories - spontaneous and traumatic - defined by what causes the lung to collapse.

A primary spontaneous pneumothorax (PSP) takes place without any underlying lung disease. It is more likely to occur in young males who are tall and thin. Smoking also increases your risk of a PSP. This type of pneumothorax can  occur if abnormal air pockets in your lungs called blebs break apart and release air.

Secondary spontaneous pneumothorax is caused because of underlying lung diseases, both chronic such as chronic obstructive pulmonary disease, cystic fibrosis, asthma, and interstitial lung disease (ILD) as well as acute conditions such as pneumonia.

Traumatic pneumothorax is caused by a blunt or penetrating chest injury. The injury or trauma to the chest area may have been caused by a gunshot, knife wound or a car accident resulting in fractured ribs. In certain medical procedures, if a lung is inadvertently punctured, the lung may collapse as well.

Who Is at Risk?

The following may put you at a higher risk for pneumothorax.

  • Lifestyle Choices
    • Scuba diving or deep-sea diving
    • Drastic changes in air pressure while flying
    • Smoking
    • Drug use, especially inhaled drugs 
  • Family history of pneumothorax

  • Marfan syndrome

  • Tall, thin young men

Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: February 18, 2026

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